A variety of systems exist for selecting content, such as advertisements, to present on web pages based on the content of such web pages. These systems often fail to select content that is relevant to, or suitable for display on, the particular page at issue. For example, an ad for a particular product or company may be selected to display on a web page containing an article that is critical of that product or company. As another example, an ad for a particular product may be displayed on a page containing an article about a completely unrelated topic merely because the product is briefly mentioned in the article. Existing systems also frequently display the selected ad in a manner that is distracting to users. These and other issues contribute to a low industry-wide click through rate of less than 1%.